Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
f. 1-phenyl-2,2-dimethylpropane

Verified step by step guidance

Step 1: Begin with benzene as the starting material. To introduce the acyl group, use the Friedel–Crafts acylation reaction. React benzene with isobutyryl chloride (CH3C(O)CH(CH3)2) in the presence of a Lewis acid catalyst such as AlCl3. This will yield 1-phenyl-2-methylpropan-1-one (a ketone).

Step 2: The product from Step 1 contains a ketone group. To reduce the ketone to a methylene group (-CH2-), use the Clemmensen reduction. Treat the ketone with zinc amalgam (Zn(Hg)) and concentrated hydrochloric acid (HCl). This will convert the ketone into 1-phenyl-2,2-dimethylpropane.

Step 3: Verify the structure of the final product to ensure it matches 1-phenyl-2,2-dimethylpropane. The benzene ring should be attached to a carbon atom that is bonded to two methyl groups and one hydrogen atom.

Step 4: Consider any potential side reactions or limitations of the Friedel–Crafts acylation and Clemmensen reduction. For example, ensure that the starting materials and reagents are compatible and that the reaction conditions are controlled to avoid over-reduction or rearrangements.

Step 5: If needed, purify the final product using techniques such as distillation or recrystallization to isolate 1-phenyl-2,2-dimethylpropane in its pure form.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Friedel–Crafts Acylation

Friedel–Crafts acylation is an electrophilic aromatic substitution reaction that introduces an acyl group into an aromatic ring. This reaction typically uses an acyl chloride and a Lewis acid catalyst, such as aluminum chloride, to form a ketone. The acyl group enhances the reactivity of the aromatic ring, allowing for further functionalization, which is crucial for synthesizing complex organic molecules.

Clemmensen Reduction

The Clemmensen reduction is a chemical reaction that reduces carbonyl groups (aldehydes and ketones) to alkanes using zinc amalgam and hydrochloric acid. This method is particularly useful for converting acylated aromatic compounds into their corresponding alkylated derivatives, facilitating the synthesis of hydrocarbons like 1-phenyl-2,2-dimethylpropane from acylated precursors.

Gatterman–Koch Synthesis

The Gatterman–Koch synthesis is a method for synthesizing aromatic aldehydes through the formylation of aromatic compounds using carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst. This reaction is significant for introducing functional groups into aromatic systems, which can be further manipulated to create complex structures, such as the desired alkane in the question.

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Propose a mechanism that shows why p-chlorotoluene reacts with sodium hydroxide at 350 °C to give a mixture of p-cresol and m-cresol.

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